docs: add Qwen3.7-Max and Qwen3.8-Max

[ai-bankofai]

Summary

• Add Qwen3.7-Max and Qwen3.8-Max model guides in English and Chinese
• Add both models to English and Chinese pricing tables
• Add both models to the Qwen sidebar group
• Include expanded Qwen3.8-Max architecture, context, reasoning, multimodal, and cache-pricing details
• Bump package version from 1.3.14 to 1.3.15

Verification

• yarn build